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go.mod,net/tstun,wgengine/netstack: implement gVisor TCP GRO for Linux (#12921)

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This commit implements TCP GRO for packets being written to gVisor on
Linux. Windows support will follow later. The wireguard-go dependency is
updated in order to make use of newly exported IP checksum functions.
gVisor is updated in order to make use of newly exported
stack.PacketBuffer GRO logic.

TCP throughput towards gVisor, i.e. TUN write direction, is dramatically
improved as a result of this commit. Benchmarks show substantial
improvement, sometimes as high as 2x. High bandwidth-delay product
paths remain receive window limited, bottlenecked by gVisor's default
TCP receive socket buffer size. This will be addressed in a  follow-on
commit.

The iperf3 results below demonstrate the effect of this commit between
two Linux computers with i5-12400 CPUs. There is roughly ~13us of round
trip latency between them.

The first result is from commit 57856fc without TCP GRO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  4.77 GBytes  4.10 Gbits/sec   20 sender
[  5]   0.00-10.00  sec  4.77 GBytes  4.10 Gbits/sec      receiver

The second result is from this commit with TCP GRO.

Starting Test: protocol: TCP, 1 streams, 131072 byte blocks
- - - - - - - - - - - - - - - - - - - - - - - - -
Test Complete. Summary Results:
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  10.6 GBytes  9.14 Gbits/sec   20 sender
[  5]   0.00-10.00  sec  10.6 GBytes  9.14 Gbits/sec      receiver

Updates #6816

Signed-off-by: Jordan Whited <jordan@tailscale.com>
This commit is contained in:
Jordan Whited
2024-08-02 10:41:10 -07:00
committed by GitHub
parent cc370314e7
commit f0230ce0b5
8 changed files with 307 additions and 48 deletions
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7
net/tstun/wrap.go
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@@ -162,6 +162,10 @@ type Wrapper struct {
PreFilterPacketInboundFromWireGuard FilterFunc
// PostFilterPacketInboundFromWireGuard is the inbound filter function that runs after the main filter.
PostFilterPacketInboundFromWireGuard FilterFunc
// EndPacketVectorInboundFromWireGuardFlush is a function that runs after all packets in a given vector
// have been handled by all filters. Filters may queue packets for the purposes of GRO, requiring an
// explicit flush.
EndPacketVectorInboundFromWireGuardFlush func()
// PreFilterPacketOutboundToWireGuardNetstackIntercept is a filter function that runs before the main filter
// for packets from the local system. This filter is populated by netstack to hook
// packets that should be handled by netstack. If set, this filter runs before
@@ -1179,6 +1183,9 @@ func (t *Wrapper) Write(buffs [][]byte, offset int) (int, error) {
}
}
}
if t.EndPacketVectorInboundFromWireGuardFlush != nil {
t.EndPacketVectorInboundFromWireGuardFlush()
}
if t.disableFilter {
i = len(buffs)
}